The present invention relates to a device for indicating the filling level in a fluid reservoir, and in particular a fluid reservoir in a vehicular hydraulic brake system, of the type having a guide tube extending into the fluid reservoir, alongside of which guide tube a float is displaceably arranged. The float includes at least one magnet by means of which at least one reed switch arranged inside the guide tube is actuatable when the float reaches a predetermined position. The reed switch is connected by electric wires protruding from the interior of the guide tube to plug-and-socket connector contacts arranged in a cap.
A device of this kind is described in the German patent application No. P 35 24 281 of the applicant in connection with a fluid reservoir for a hydraulic brake system. The float for indicating the filling level in that device requires a complicated production technique and is considered less advantageous. The float is made of a thermoplastic plastic material and is provided with at least one axial circular indentation formed in the float's end face. The diameter of the indentation corresponds with that of a ring-shaped permanent magnet which is accommodated therein. In order to secure the permanent magnet in its installed position during the assembly and subsequent operation, the outer rim of the indentation must be sealed while the float is being heated which increases production costs of that fluid reservoir considerably.